Mass transit vehicles, such as trolley cars, buses, etc., typically have seats aligned at the lateral sides of the vehicle, with a central aisle and floor extending along the vehicle. In order to facilitate entering and exiting from the vehicle, it is desirable to have the floor and aisle positioned relatively low to the ground. This provides faster cycle time during stops and facilitates boarding for all passengers, especially children, the elderly and disabled passengers.
Mass transit vehicles typically have several axles that support, drive and steer the vehicle. Many such vehicles provide a rigid drive axle having a central or offset input that is coupled to a driveline. Disadvantageously, this arrangement prohibits lowering the vehicle floor to desired levels due to the use of a rigid axle housing in combination with the position of the input and the associated driveline.
One solution has replaced a traditional rigid drive axle configuration with independent wheel drives. In this configuration, electric motors are mounted at each wheel, allowing the floor to be lowered closer to ground level. When electric motors are utilized at each wheel, typically a double reduction gear assembly is required to achieve desired levels of output torque and speed. The double reduction gear assembly typically includes a first reduction gear set that is coupled to the electric motor and a second reduction gear set that is incorporated into the wheel. The second reduction gear set is typically a planetary gear set that is directly incorporated into a wheel hub at each wheel. The first reduction gear set is mounted inboard of the wheel hub. The wheel hub is supported on wheel bearings and also supports a brake component, such as a brake rotor or brake drum.
One disadvantage with this configuration is that when service operations are required for brake components, the wheel hub must be disassembled from the wheel. Disassembly of the wheel hub requires removal of the planetary gear set and associated wheel bearings. This is time consuming and increases maintenance and service costs.
Accordingly, it is desirable to provide vehicle wheel assembly for a low floor vehicle application that does not require removal of any gear reduction sets or wheel bearings in order to service brake components.